It is often desirable to partially seal the mouth of a tubular fitting so as to allow the fitting to breathe. For example, to sterilize medical devices, sterilizing gases are pumped through the devices and allowed to slowly escape through breather caps installed on fittings. It is also desirable at times to fully seal the same tubular fittings, e.g., when particular fittings are not used during operation of a device. And tubular fittings generally need to be fitted with shipping caps to protect both the fittings and packaging from breakage. Conventionally a number of caps have been employed to serve these multiple purposes. Pliable plastisol caps have been used for shipping and in some instances for breathing, and, with barbed fittings, sealing has been accomplished by clamping the end of a short piece of installed tubing. In addition to the disadvantage of employing separate fittings, plastisol caps tend to work themselves off the fittings during shipment and to leave shreds of plastisol in the fitting interiors.
DeVincent et al. U.S. Pat. No. 4,035,005 shows a hose coupling comprising a pair of mating fittings. One of the fittings has axially spaced pairs of inwardly protruding tangs which snap past a camming surface on the other fitting to lock the fittings in either a venting or sealing position. Sealing is achieved by inserting the other fitting past both pairs of tangs so as to squeeze an O-ring between an exterior surface of the one fitting and an interior surface of the other fitting. Inserting the other fitting past only the first pair of tangs establishes the venting position.
Wirz et al. U.S. Pat. No. 1,890,011 shows a hose coupling with lugs on one fitting received by bayonet slots on the other, for axially forcing the two fittings together against an internal seal when one fitting is twisted relative to the other.
Stone U.S. Pat. No. 512,457 is broadly similar to Wirz, and Bradley U.S. Pat. No. 305,140 shows the same lug and bayonet slot arrangement applied to fastening together two lightning rod sections.
Jacobs U.S. Pat. No. 3,585,654 and Heck U.S. Pat. No. 3,055,366 show a lug and bayonet slot arrangement used only for retention and not for sealing.